1. Field of the Invention
The present invention relates to a vaporizing apparatus for generating a process gas from a liquid material, and a semiconductor processing system. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or a glass substrate used for an FPD (Flat Panel Display), e.g., an LCD (Liquid Crystal Display), by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
2. Description of the Related Art
A film formation process for forming a predetermined film on the surface of a semiconductor wafer is performed in manufacturing semiconductor devices. For example, a process of this kind is performed, using a low-pressure CVD (Chemical Vapor Deposition) apparatus. In low-pressure CVD apparatuses, a source material is supplied in a gaseous state to promote a chemical reaction, thereby depositing a thin film on the surface of a wafer. In apparatuses of this kind, there is a case where a process gas is generated by vaporizing a liquid material, and is supplied into a process chamber as a film formation gas.
Examples of a film formation process using a process gas generated by vaporizing a liquid material are as follows. Specifically, a process gas generated by vaporizing TEOS (Si(OC2HO5)4: tetraethoxysilane) and oxygen (O2) gas are used to form an SiO2 film. A process gas generated by vaporizing hexachlorodisilane (Si2Cl6) and ammonia (NH3) gas are used to form a silicon nitride (Si3N4) film.
Further, in some processes, a metal-organic compound (complex compound) is used to form a film of this metal. Examples of a film formation process of this type are as follows. Specifically, a process gas generated by vaporizing a hafnium-containing liquid material and oxygen gas are used to form a hafnium oxide film. Process gases generated by vaporizing liquid materials containing titanium (Ti), strontium (Sr), and barium (Ba) and oxygen gas are used to form a BST (barium strontium titanium) oxide film.
Conventionally, where a liquid material having a high vapor pressure, such as TEOS, is used, in-liquid particles contained in the liquid material (about 3,000/ml) are vaporized by a baking method. In this case, only vapor is supplied into a process chamber, while the in-liquid particles are left in the liquid material stored in the heating vessel. However, a liquid material having a low vapor pressure, such as a hafnium-containing material, is difficult to vaporize by a baking method, because the gas thereof has a low decomposition temperature. Further, the liquid material is stored for a long time in a tank set at a high temperature, and is thereby denatured. Accordingly, in order to promote vaporization of a liquid material, a spray type is used such that the liquid material is supplied along with a carrier gas in an atomized state from an injector into a vaporizing chamber heated to a predetermined temperature. However, in this case, since in-liquid particles are sent to the injector, a filter for trapping particles is required inside the vaporizing chamber.
Further, because of diversification in the design of semiconductor devices, various metal organic compounds have come into use as liquid materials. For example, an organic compound of Hf, Zr, or St has a low vapor pressure that is less than 1/10 of that of TEOS. Where a liquid material having such a low vapor pressure is used, the liquid material cannot be vaporized well, so a non-vaporized component (mist) inevitably remains. If a process gas contains mist, particles may be deposited on a wafer. Accordingly, it is necessary to dispose a filter near the outlet of a vaporizer or in a gas supply passage.
In general, such a filter is fixed by a fixing member on a container for forming the vaporizing chamber of a vaporizer. The filter is heated from around through the fixing member by a heater built in the container. Patent Document 1 (Jpn. Pat. Appln. KOKAI Publication No. 2004-211183 (paragraph 0012 and FIG. 2)) discloses, a vaporizer including a filter disposed to cover an outlet port formed in a sidewall of a chamber body. This filter is fixed by bolts on the chamber body so that the backside thereof is in close contact with a wall surface. This filter is heated by a heater disposed on the chamber body near the wall surface on which the filter is attached.